From 5563d760ef7849c88f12d4d39d6e7f2b5c305703 Mon Sep 17 00:00:00 2001
From: Matt Borland <matt@mattborland.com>
Date: Mon, 27 Mar 2023 16:16:54 +0200
Subject: [PATCH] Implement general notation for non-integer results

---
 include/boost/charconv/detail/floff.hpp | 22 +++++++++++++++++++---
 src/to_chars.cpp                        |  9 +++++++--
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/include/boost/charconv/detail/floff.hpp b/include/boost/charconv/detail/floff.hpp
index 515944f..efa2bd8 100644
--- a/include/boost/charconv/detail/floff.hpp
+++ b/include/boost/charconv/detail/floff.hpp
@@ -22,6 +22,7 @@
 #define BOOST_CHARCONV_DETAIL_FLOFF
 
 #include <boost/charconv/detail/config.hpp>
+#include <boost/charconv/chars_format.hpp>
 #include <type_traits>
 #include <limits>
 #include <cassert>
@@ -2294,7 +2295,8 @@ namespace jkj { namespace floff {
     // precision means the number of decimal significand digits minus 1.
     // Assumes round-to-nearest, tie-to-even rounding.
     template <class MainCache = main_cache_full, class ExtendedCache>
-    JKJ_SAFEBUFFERS char* floff(double const x, int const precision, char* buffer) noexcept {
+    JKJ_SAFEBUFFERS char* floff(double const x, int const precision, char* buffer, boost::charconv::chars_format fmt) noexcept 
+    {
         assert(precision >= 0);
         using namespace detail;
 
@@ -4562,14 +4564,28 @@ case n:
         /////////////////////////////////////////////////////////////////////////////////////////////////
 
     fill_remaining_digits_with_0s:
-        std::memset(buffer, '0', remaining_digits);
-        buffer += remaining_digits;
+        if (fmt != boost::charconv::chars_format::general)
+        {
+            std::memset(buffer, '0', remaining_digits);
+            buffer += remaining_digits;
+        }
 
     insert_decimal_dot:
         buffer_starting_pos[0] = buffer_starting_pos[1];
         buffer_starting_pos[1] = '.';
 
     print_exponent_and_return:
+        if (fmt == boost::charconv::chars_format::general)
+        {
+            --buffer;
+            while (*buffer == '0')
+            {
+                --buffer;
+            }
+
+            ++buffer;
+        }
+        
         if (decimal_exponent >= 0) {
             std::memcpy(buffer, "e+", 2);
         }
diff --git a/src/to_chars.cpp b/src/to_chars.cpp
index 0ca394a..2e1f880 100644
--- a/src/to_chars.cpp
+++ b/src/to_chars.cpp
@@ -290,7 +290,12 @@ boost::charconv::to_chars_result boost::charconv::to_chars( char* first, char* l
 boost::charconv::to_chars_result boost::charconv::to_chars(char* first, char* last, double value, boost::charconv::chars_format fmt, int precision) noexcept
 {
     
-    if (fmt == boost::charconv::chars_format::scientific)
+    if (fmt == boost::charconv::chars_format::general)
+    {
+        auto* ptr = jkj::floff::floff<jkj::floff::main_cache_full, jkj::floff::extended_cache_long>(value, std::numeric_limits<double>::max_digits10 - 1, first, fmt);
+        return { ptr, 0 };
+    }
+    else if (fmt == boost::charconv::chars_format::scientific)
     {
         if (precision == -1)
         {
@@ -300,7 +305,7 @@ boost::charconv::to_chars_result boost::charconv::to_chars(char* first, char* la
         {
             return { first, EOVERFLOW };
         }
-        auto* ptr = jkj::floff::floff<jkj::floff::main_cache_full, jkj::floff::extended_cache_long>(value, precision, first);
+        auto* ptr = jkj::floff::floff<jkj::floff::main_cache_full, jkj::floff::extended_cache_long>(value, precision, first, fmt);
         return { ptr, 0 };
     }
     else